1. Field of the Invention
This invention relates to an image projecting device to project an erected image of an object to be projected onto a projecting surface. More particularly, the invention is concerned with an ommateal image projector of a type, in which a single or a plurality of bar lenses having a longer length in the direction of the optical axis than the effective lens diameter thereof are arranged.
2. Description of the Prior Art
U.S. Pat. No. 3,605,593 teaches an image projecting device which projects an entire image of an object to be projected onto a projecting surface by arranging small lenses in a single or a plurality of rows, each of the small lenses projecting a partial image of the object to be projected onto the projecting surface.
This image projecting device has such an advantage that, in comparison with an image projector to project onto a projecting surface the entire image of the object to be projected by a single lens, a conjugate length, i.e., a length between the object to be projected and the image projecting surface, becomes short. On account of this, such ommateal image projector is used for scanning of an image original in an image reproduction apparatus, the overall size of which is desired to be reduced. For example, British Pat. No. 1,125,887 and U.S. Pat. No. 3,584,950 disclose image reproduction apparatuses which form an erecting image of the entire image original on a photosensitive material by moving the ommateal lens system relative to the image original and the photosensitive material.
Further, British Pat. No. 1,462,085 discloses an ommateal reflection type image projecting device which forms an overall image of an image original by projecting partial images of an object to be projected onto a mirror surface by use of individual small lenses constituting the ommateal lens system, and then re-forming the partial images formed on the mirror surface on the image projecting surface by the same small lenses.
The present invention is concerned with improvement in the ommateal reflection type image projecting device in this British patent, the characteristic point of which resides in the use of bar lenses for the ommateal lens system, each lens having a longer length in the direction of the optical axis thereof than the effective lens diameter.
Such bar lens has already been disclosed in U.S. Pat. No. 3,252,902. In addition, improvement in such bar lens has been done by the present inventors, and has been applied for a patent in the United States of America under application Ser. No. 889,404 (filed Mar. 23, 1978) and in the Federal Republic of Germany (West Germany) under application Ser. No. P 28 13 763.5 (filed Mar. 30, 1978).